Animal Diversity II: Vertebrates

• Key features of chordates

• Major phyla of chordates

Kingdom Animalia

Phylogeny

Phylum Chordata

• All are deuterostomes(2nd opening a mouth)

• Notochord: stiff flexible rod

• Dorsal hollow nerve cord

• Pharyngeal gill slits• Post-anal tail

Invertebrate chordates

• Lancelet• Tunicates

Vertebrates

• Have a backbone• Bone or cartilage• Paired appendages• Size and complexity of the brain

Major Phyla

• Fish: two chambered heart

• Jawless fish

• Hagfish: not true vertebrate

• Lamprey

Jawed fish

• Cartilaginous fish• Chrondrichthyes• Sharks• Skates • Rays• No bone

Bony fish

• Most diverse vertebrate group• Class Osteichthyes• 17,000 spp

Swim bladder for buoyancy

Lungfish

Here's a living species of Lepidosiren. If you look carefully, you can see the fourslender "fins" of this fish, which are homologous to the four legs of terrestrial vertebrates.

Amphibians

• Live aquatic and terrestrial• Three chambered heart• Lungs replace gills• Supplemented by moist skin• Reproduction requires water

Diversity of amphibians

Reptila

• 250 million years ago• Scales• Shelled eggs• Amniote egg: enclose embryo in fluid• More efficient lungs• Birds are feathered reptiles

Reptiles: Birds

•Archaeopteryx: transition fossil•Hollow bones•Shelled egg•Maintain body temperature•Four chambered heart•Air sacs

Class Mammalia

• 250 million years ago• 65 million years diversified• Mammary glands• Hair• Three groups• Monotremes: egg laying• Marsupials: pouches• Placentals: longer uterine development

Monotremes & Marsupials

Diversity of Mammals

Humans